1. Field of the Invention
The present invention relates to barrels for holding parts during electroplating and, in particular, to barrel construction utilizing perforated panels.
2. Description of Related Art
Barrels with a polygonal axial cross-section have long been used in electroplating small components. Such barrels typically have six sides comprised of perforated rectangular panels, at least one of which may be removed to provide access to the interior of the drum for filling and removing parts. The drums are rotated along an axis while being at least partially immersed in a bath or solution for electroplating or otherwise chemically treating parts. As they are tumbled and plated within the solution, the individual metal parts within the barrel are retained within the barrel (due to the perforation size being less than the part size) and are simultaneously exposed to the electroplating solution which enters through the perforations in the panels.
Such barrels are normally removable from the plating tank in which they operate for loading and unloading the parts. It is not unusual for such barrels to be used for temporary part storage prior to or subsequent to the plating treatment in the bath. The barrels may be moved around the plating facility, for example, by forklift truck, and may be stacked on shelving or on top of one another. As a consequence, the barrels are subject to rough handling and the panels making up the barrel often impact against other hard objects. Since it is generally necessary to utilize non-electrically conductive materials for the panels, e.g., plastics or other non-metallic materials, and the brittleness which occurs with age and exposure to plating solutions, the panels are often weak and may easily sustain damage.
Because of the need to maintain a relatively smooth surface on the interior of the barrel while providing adequate strength for the perforations and the panels themselves, some prior art plating barrels have utilized panels having ribs extending outward from the barrel, which ribs enclose one or more perforations in the panel. An example of such a plating barrel panel is shown in U.S. Pat. No. 3,936,985 which discloses a panel having a rib structure in the form of a rectangular grid. Likewise, U.S. Pat. No. 4,018,427 discloses a rectangular grid structure for the ribs which includes a second set of cross ribs which are shallower than the primary set of cross ribs. U.S. Pat. No. 3,953,633 also discloses panels having a grid-like arrangement of ribs. U.S. Pat. Nos. 4,422,774 and 4,162,951 disclose other plating barrel styles utilizing grid-like ribs on the side panels.
While such rectangular grid structures partially fulfill a long felt need for improved panel structures, they do not provide sufficient resistance to rough handling typically encountered in plating facilities. As a result, alternative panels for barrels have used thick panel sides for increased resistance to damage.
Another problem encountered with prior art plating barrels is bath solution "drag out" i.e., the retention of bath solution in the perforations due to a capillary effect. Thick wall plating barrels show good resistance to damage, but they increase the amount of bath solution retained in the barrel which is dragged out and transferred from one bath to the other or otherwise lost from the system itself. Such dragged out solution has to be replenished, creating additional plating expense, and, because of the nature of some plating baths, contributes to toxic waste which must be handled and neutralized. Thin wall plating barrel panels used prior to the present invention provide some improvement in this area, but have not be able to withstand the damage done in a factory environment.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an improved plating barrel configuration which has improved durability in a manufacturing environment.
It is another object of the present invention to provide a plating barrel panel with ribs which provides better resistance to impact and decreases the amount of damage to the ribs themselves.
It is a further object of the invention to provide a plating barrel side panel that has sufficient perforations for bath solution to enter the barrel, but has a lower hole volume in order to reduce the potential for drag out of plating bath chemicals.
It is yet another object of the present invention to provide a high impact resistance plating barrel panel which has thin wall configuration around the panel perforations.
It is a further object of the present invention to provide a plating barrel panel configuration which may be easily constructed and retrofitted to existing barrels.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.